1. Technical Field
The present invention relates to an electronic timepiece with an internal antenna.
2. Related Art
Electronic timepieces that receive signals from positioning information satellites such as GPS (Global Positioning System) satellites to display time accurately are known from the literature. Such electronic timepieces commonly have a ring-shaped antenna for receiving radio signals from the positioning information satellites. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2011-21929.
In this type of electronic timepiece, the ring-shaped antenna is disposed inside the outside case around the time display part (such as the dial) of the electronic timepiece. The antenna is also commonly covered from above by a dial ring for aesthetic purposes. The dial ring is also usually plastic or other non-conductive material in order to achieve better reception performance in the antenna.
The antenna can conceivably be held by the outside case in order to maintain a specific distance between the antenna and the case in timepieces according to the related art, but because suitable reception performance must be maintained in the antenna when driving an electronic timepiece with an internal antenna, the antenna is typically fixed in position relative to the movement during the manufacturing process.
However, if the outside case member located close to the antenna is metal, and the ring-shaped antenna is disposed close to the metal case, the resonance frequency characteristic of the antenna may vary. To maintain good signal reception performance in the antenna of an electronic timepiece with internal antenna, maintaining a specific distance between the antenna and the case, and keeping the effect of the case on reception performance constant, are therefore important.
Because even the plastic materials used for the dial ring have slight permittivity, the resonance frequency of the antenna disposed near the dial ring fluctuates and affects the signal reception performance of the antenna. To maintain good signal reception performance in the antenna of an electronic timepiece with internal antenna, maintaining a specific distance between the antenna and the dial ring, and keeping the effect of the dial ring on reception performance constant, are therefore important.